1. Field of the Invention
The present invention relates to an image processing method and apparatus, and more particularly to an image processing method and apparatus which is applicable to a printer, digital copier or facsimile which prints image data from an image scanner, a computer or the like.
2. Description of the Related Arts
In a conventional digital copier, an original image is irradiated by a light source such as a halogen lamp and the reflection of the original image is read by a solid image pickup device such as a CCD (charge coupled device). The image signal which was photoelectrically transformed by the solid image pickup device is further transformed into a digital signal. After a predetermined correction processing is performed on the digital signal, the corrected image signal is output to a printer, a laser beam printer, thermal printer, or ink jet printer. Thus, the recording image is formed on a recording medium such as recording paper.
Since there is a case of copying a color original image by a monochrome digital copier, the image output of the color image is required to carry more information than the output of a black and white image. To copy such an image, a digital full-color copier and a one-point color copier capable of copying a multiple-color image in color have been developed.
On the other hand, in the case where a color image is read and the image data is output by the recording apparatus and printed in black and white, there is a copier which reads the color image by a color sensor, and the color of the original image is discriminated, and the pattern data corresponding to each color is output on the basis of the result of color discrimination. Thus, art in which the duplication is produced in a manner such that the difference of colors in the original image is expressed by the difference of the printed patterns is known.
However, in the above described apparatus which discriminates colors of an original image and duplicates the image by generating pattern data corresponding to the discriminated color, there is a drawback in that the printed result is not clear because, in the point where two colors are mixed or the gradation area where colors are continuously changing, the two kinds of patterns coexist at the changing point. This type of problem cannot be ignored when a color is incorrectly discriminated, particularly when a shift of color reading position has occurred in a scanner.